Purpose: This article aimed to investigate the mechanism by which MALAT1  and miR-129  affected the development of osteosarcoma.
Methods: Tumor tissues and adjacent tissues of 23 osteosarcoma patients were collected. Normal osteoblasts hFOB1.19 and osteosarcoma cells MG63 were cultured. MG63 cells were transfected and grouped: si-negative control (NC) group, si-MALAT1 group, miR-129 NC group, miR-129 mimics group, p-Empty vector group, p-MALAT1 group, p-MALAT1+ miR-129 mimics group, and p-MALAT1+ si-TGIF2 group. Luciferase reporter assay, Cell Counting Kit-8 assay, Transwell assay, quantitative reverse transcription PCR, Western blot, and Pearson correlation analysis were performed.
Results: MALAT1  expression in tumor tissues and MG63 cells was increased (P <0.01). High MALAT1  expression predicted poor prognosis of osteosarcoma patients. MG63 cells of si-MALAT1 group exhibited much lower cell viability, migration, and invasive cell numbers when compared with si-NC group (P <0.01). For MG63 cells of miR-129 mimics group, they had markedly lower cell viability, migration, and invasive cell numbers than miR-129 NC group (P <0.01). miR-129  was targetedly and negatively regulated by MALAT1 . TGIF2 , which was targetedly and negatively regulated by miR-129 , was overexpressed in tumor tissues and MG63 cells (P <0.01). miR-129  overexpresison and TGIF2  downregulation significantly reversed the enhanced cell viability, migration, and invasion induced by MALAT1  (P <0.01).
Conclusion: MALAT1  promotes TGIF2  expression through negative regulation of miR-129 , which further promotes the proliferation, migration, and invasion of MG63 cells.
Keywords: MALAT1 , miR-129 , TGIF2 , osteosarcoma, invasion, prognosis